The 4th Many Hosts of Mycobacteria meeting will be held at the Education Center at Busch Gardens in Tampa, Florida in February 2011. This meeting is co-organized by Michelle Larsen (Albert Einstein College of Medicine) and Ray Waters (National Animal Disease Center, USDA) in consultation with Christine Sizemore (NIAID). Ray Ball (Director of Veterinary Services, Busch Gardens, Florida) is the local host for the 4th Many Hosts of Mycobacteria meeting and a member of the planning committee. The purpose of the meeting series is to bring together basic researchers, clinicians, and veterinary medicine researchers that study mycobacterial diseases/hosts. The previous three Many Hosts of Mycobacteria meetings have been held at the National Animal Disease Center in Ames, Iowa (September 2007), Gettysburg, Pennsylvania (September 2008), and the historic former leprosy sanatorium in Carville, Louisiana (November 2009). These meetings are small (~70-80 attendees) and have open registration. A workshop format is used for the meetings to foster open and interactive discussion. The diverse perspectives are exemplified by inclusion of thirteen models (mouse, guinea pig, cotton rat, rabbit, badger, possum, armadillo, fish, deer, cattle, elephant, monkeys and humans) and both experimental and natural infections (Tuberculosis from M. bovis and M. tuberculosis;Leprosy from M. leprae, Johnes Disease from M. avium paratuberculosis, and general mycobacterial infections from M. ulcerans and non-tuberculous mycobacteria). The focus of the Iowa meeting was on the utility and limitations of these models in understanding myobacterial disease, pathogenesis, and vaccine development. The Gettysburg meeting focused on immunopathology, and the theme of the Carville was comparative mycobacteriology. The theme of the Busch Gardens Many Hosts of Mycobacteria meeting will be biomakers. We target inclusion of young investigators as speakers and moderators for these meetings to foster discussion of new ideas and allow for development of collaboration between research groups that do not typically interact with each other. Project Narrative: The Many Hosts of Mycobacteria meeting is a small (~70-80 attendees) workshop-style meeting with open registration that targets inclusion of young investigators as speakers and moderators. The purpose of the meeting is to bring together basic researchers, clinicians, and veterinary medicine researchers that work on mycobacterial diseases such as Tuberculosis, Leprosy, and Johnes Disease in a wide range of natural and experimental infection hosts (mouse, guinea pig, cotton rat, rabbit, badger, possum, armadillo, fish, deer, cattle, zoo species, monkeys and humans). The topics and format of this meeting are meant to foster lively discussion to facilitate our understanding of mycobacterial disease across many species.